Substrate for suspension, and production process thereof

ABSTRACT

The present invention provides a substrate for suspension that includes a first structural part including a metal supporting substrate, an insulating layer, a wiring layer, and a cover layer, and a second structural part formed so as to extend continuously from the first structural part and has no metal supporting substrate. A position of an edge of an upper surface of the insulating layer coincides with a position of an edge of the lower surface of the cover layer or the position of the edge of the upper surface of the insulating layer is positioned on a side closer to the wiring layer than to the position of the edge of the lower surface of the cover layer at a boundary region between the first structural part and the second structural part.

TECHNICAL FIELD

The present invention relates to a substrate for suspension whichrestrains the generation of cracks in the insulating layer at theboundary region between a region where a metal supporting substrateexists and a region where no metal supporting substrate exist. Thepresent invention also relates to a substrate for suspension whichreduces the influence of cracks generated in the insulating layer at theboundary region between a region where a metal supporting substrateexists and a region where no metal supporting substrate exist.

BACKGROUND ART

In recent years, there have been great demands for the increases in theamount of information processing and in information processing speed forpersonal computers under such circumstances including widespread use ofthe internet. Along with this, it has come to be necessary that harddisc drives (HDD) incorporated in a personal computer be increased incapacity and in information communication speed. For this, the substratefor suspension (flexure (integrated lead suspension)) used in HDDs needto have advanced functions.

As such a substrate for suspension, for example, Japanese PatentLaid-Open No. 2007-213793 discloses a flexure comprising a sliderbonding pad part (tongue section), an outrigger and a crossbar. Further,wiring is formed on the outrigger in Japanese Patent Laid-Open No.2007-213793. Moreover, Japanese Patent Laid-Open No. H11-039626discloses a disk device suspension comprising a wiring layer arrangedbetween the tongue section and the outrigger section. Japanese PatentLaid-Open No. 2007-287296 also discloses an out trace type flexure inwhich a trace member (wiring layer) is extended around the outside theoutrigger section. Japanese Patent Laid-Open No. 2008-041241 alsodiscloses a gimbal structure comprising a trace support tab thatsupports a conductive trace (wiring layer).

SUMMARY OF INVENTION Technical Problem

In a conventional substrate for suspension, a wiring layer is formed ona metal supporting substrate with an insulating layer interposedtherebetween. As substrate for suspensions having advanced functions aredeveloped (for example, substrates for suspension having a lowerstiffness are developed), a method is currently adopted in which a partof a metal supporting substrate is positively removed. When apart of themetal supporting substrate is removed, this causes the problemconcerning easy generation of cracks to the insulating layer. It isbecause stress is concentrated on the insulating layer part formed abovethe boundary region between a region where a metal supporting substrateexists and a region where no metal supporting substrate exist.

The present invention has been made in view of the above problems and itis a primary object of the present invention to provide a substrate forsuspension which restrains the generation of cracks in the insulatinglayer corresponding to the boundary region between a region where ametal supporting substrate exists and a region where no metal supportingsubstrate exist. Also, the present invention has been made in view ofthe above problems and it is a primary object of the present inventionto provide a substrate for suspension which reduces the influence ofcracks generated in the insulating layer at the boundary region betweena region where a metal supporting substrate exists and a region where nometal supporting substrate exist.

Solution to Problem

In order to solve the above problem, the present invention provides asubstrate for suspension comprising a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, and a cover layer formed to coverthe wiring layer, wherein the substrate for suspension comprises a firststructural part including the metal supporting substrate, the insulatinglayer, the wiring layer, and the cover layer, and a second structuralpart formed so as to extend continuously from the first structural partand has no metal supporting substrate, and wherein a position of an edgeof an upper surface of the insulating layer coincides with a position ofan edge of a lower surface of the cover layer or the position of theedge of the upper surface of the insulating layer is positioned on aside closer to the wiring layer than to the edge of the lower surface ofthe cover layer at a boundary region between the first structural partand the second structural part.

According to the present invention, the position of the edge of theupper surface of the insulating layer coincides with the position of theedge of the lower surface of the cover layer or is positioned on theside closer to the wiring layer than to the edge of the lower surface ofthe cover layer at the boundary region and therefore, the generation ofcracks in the insulating layer can be restrained. For this, the breakingof wiring layer caused by stress concentration can be prevented.

In the above invention, it is preferable that the metal supportingsubstrate has a tongue section mounting for a device and an outriggersection positioned outside the tongue section, and the wiring layer isformed between the tongue section and the outrigger section in planarview. This is because that although cracks are easily generated in theinsulating layer lying under the wiring layer at the boundary region inwhich the wiring layer is formed, the influence of the generation ofcracks can be efficiently reduced.

In the above invention, it is preferable that the metal supportingsubstrate has a crossbar connecting the tongue section with theoutrigger section; and the metal supporting substrate of the firststructural part is the crossbar.

In the above invention, it is preferable that the metal supportingsubstrate has a trace support tab on an end surface of the tonguesection side of the outrigger section and the metal supporting substrateof the first structural part is the trace support tab.

In the above invention, it is preferable that the metal supportingsubstrate has a base part supporting a bottom of the outrigger sectionand the metal supporting substrate of the first structural part is thebase part.

In the above invention, the metal supporting substrate of the firststructural part is preferably the tongue section.

Also, in the present invention, there is provided a substrate forsuspension comprising a metal supporting substrate, an insulating layerformed on the metal supporting substrate, a wiring layer formed on theinsulating layer, and a cover layer formed to cover the wiring layer,wherein the substrate for suspension comprises a first structural partincluding the metal supporting substrate, the insulating layer, thewiring layer, and the cover layer, and a second structural part formedso as to extend continuously from the first structural part and has nometal supporting substrate, wherein at least one of a width from an edgeof the wiring layer to an edge of the insulating layer and a width fromthe edge of the wiring layer to an edge of the cover layer is locallylarge in planar view at a boundary region between the first structuralpart and the second structural part.

According to the present invention, at least one of the width from theedge of the wiring layer to the edge of the insulating layer and thewidth from the edge of the wiring layer to the edge of the cover layeris made locally large in planar view at the boundary region, andtherefore, the influence of cracks generated in the insulating layer canbe reduced. The wiring layer can be therefore prevented from breaking bystress concentration.

In the above invention, a position of the edge of the insulating layerpreferably coincides with a position of the edge of the cover layer atthe boundary region. This is because the generation of cracks can beintrinsically restrained.

In the above invention, a curved structural section is preferably formedso as to include the boundary region in planar view, on at least one ofthe insulating layer and the cover layer. This is because that theexistence of the curved structural section allows the dispersion ofstress, thereby enabling further restriction on the generation of cracksin the insulating layer at the boundary region.

Also, in the present invention, there is provided a substrate forsuspension comprising a metal supporting substrate, an insulating layerformed on the metal supporting substrate, a wiring layer formed on theinsulating layer, and a cover layer formed to cover the wiring layer,wherein the substrate for suspension comprises a first structural partincluding the metal supporting substrate, the insulating layer, thewiring layer, and the cover layer, and a second structural part formedto extend continuously from the first structural part and has no metalsupporting substrate, wherein an auxiliary wiring layer is formedbetween an edge of the wiring layer and an edge of the insulating layerin planar view at the boundary region between the first structural partand the second structural part.

According to the above invention, the auxiliary wiring layer is formedbetween the edge of the wiring layer and the edge of the insulatinglayer in planar view at the boundary region so that the influence ofcracks generated in the insulating layer can be reduced. The wiringlayer can be therefore prevented from breaking or the like by stressconcentration.

In the above invention, the surface of the auxiliary wiring layer ispreferably covered with the cover layer.

In the above invention, a wiring plating section is preferably formed ona surface of the auxiliary wiring layer.

In the above invention, it is preferable that at least one of a widthfrom the edge of the wiring layer to the edge of the insulating layerand a width from the edge of the wiring layer to the edge of the coverlayer is locally large in planar view at the boundary region. This isbecause the influence of cracks generated in the insulating layer can bemore reduced.

In the above invention, it is preferable that the metal supportingsubstrate has a tongue section mounting for a device and an outriggersection positioned outside the tongue section, and the wiring layer isformed between the tongue section and the outrigger section in planarview. This is because that although cracks are easily generated in theinsulating layer at the boundary region where the wiring layer isformed, the influence of the generation of cracks can be efficientlyreduced.

In the above invention, it is preferable that the metal supportingsubstrate has a crossbar connecting the tongue section with theoutrigger section and the metal supporting substrate of the firststructural part is the crossbar.

In the above invention, it is preferable that the metal supportingsubstrate has a trace support tab on an end surface of the tonguesection side of the outrigger section; and the metal supportingsubstrate of the first structural part is the trace support tab.

In the above invention, it is preferable that the metal supportingsubstrate has a base part supporting a bottom of the outrigger sectionand the metal supporting substrate of the first structural part is thebase part.

In the above invention, the metal supporting substrate of the firststructural part is preferably the tongue section.

Also, in the present invention, there is provided a production processof substrate for suspension comprising: a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, a cover layer formed to cover thewiring layer, a first structural part including the metal supportingsubstrate, the insulating layer, the wiring layer, and the cover layer,and a second structural part formed to extend continuously from thefirst structural part and has no metal supporting substrate, the methodcomprises a step of: forming the insulating layer by carrying out wetetching such that a position of an edge of an upper surface of theinsulating layer coincides with a position of an edge of a lower surfaceof the cover layer or the position of the edge of the upper surface ofthe insulating layer is positioned on a side closer to the wiring layerthan to the edge of the lower surface of the cover layer at the boundaryregion between the first structural part and the second structural part.

According to the present invention, wet etching is carried out such thatthe position of the edge of the upper surface of the insulating layercoincides with the position of the edge of the lower surface of thecover layer or is positioned on the side closer to the wiring layer thanto the edge of the lower surface of the cover layer to form theinsulating layer so that a substrate for suspension which restrains thegeneration of cracks in the insulating layer can be obtained.

In the above invention, it is preferable to form the metal supportingsubstrate having a tongue section mounting for a device and an outriggersection positioned outside the tongue section, and to form the wiringlayer between the tongue section and the outrigger section in planarview. This is because that although cracks are easily generated in suchan insulating layer lying under the wiring layer at the boundary regionwhere this wiring layer is formed, the influence of the generation ofcracks can be efficiently reduced.

In the above invention, the cover layer is preferably used as a resistlayer in the insulating layer formation step. This is because it isunnecessary to form a resist layer separately. Moreover, the insulatinglayer is highly bonded with the cover layer in usual from the viewpointof securing the durability required for a product. Therefore,infiltration of an etching solution between both of the layers can beprevented, and the angle θ of the lower end section of the insulatinglayer can be increased.

In the above invention, the material of the cover layer is preferably amaterial having a lower etching rate for the etching solution than thematerial of the wiring layer. This is because such a material is usefulfor the resist layer.

Also, in the present invention, there is provided a production processof substrate for suspension comprising: a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, a cover layer formed to cover thewiring layer, a first structural part including the metal supportingsubstrate, the insulating layer, the wiring layer, and the cover layer,and a second structural part formed so as to extend continuously fromthe first structural part and has no metal supporting substrate, themethod comprises a step of forming at least one of the insulating layerand the cover layer such that at least one of a width from an edge ofthe wiring layer to an edge of the insulating layer and a width from theedge of the wiring layer to an edge of the cover layer is locally largein planar view at a boundary region between the first structural partand the second structural part.

According to the present invention, at least one of the insulating layerand the cover layer is formed such that at least one of the width fromthe edge of the wiring layer to the edge of the insulating layer and thewidth from the edge of the wiring layer to the edge of the cover layeris locally large in planar view at the boundary region, and therefore,the substrate for suspension with reduced influence of cracks generatedin the insulating layer can be obtained.

In the above invention, it is preferable to form the insulating layerand the cover layer such that a position of the edge of the insulatinglayer coincides with a position of the edge of the cover layer at theboundary region. This is because the generation of cracks can beintrinsically restrained.

Also, in the present invention, there is provided a production processof substrate for suspension comprising: a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, and a cover layer formed to coverthe wiring layer, a first structural part including the metal supportingsubstrate, the insulating layer, the wiring layer, the cover layer, anda second structural part formed so as to extend continuously from thefirst structural part and has no metal supporting substrate, the methodcomprises a step of: a wiring layer formation step of forming anauxiliary wiring layer between an edge of the wiring layer and the edgeof the insulating layer in planar view at the boundary region betweenthe first structural part and the second structural part.

According to the above invention, an auxiliary wiring layer is formedbetween the edge of the wiring layer and the edge of the insulatinglayer at the boundary region and therefore, a substrate for suspensionwith reduced influence of cracks generated in the insulating layer canbe obtained.

In the above invention, the wiring layer and auxiliary wiring layer arepreferably formed simultaneously in the wiring layer formation step.This is because the production process can be simplified.

In the above invention, it is preferable to form a metal supportingsubstrate comprising a tongue section mounting for a device and anoutrigger section positioned outside the tongue section and to form thewiring layer between the tongue section and the outrigger section inplanar view. This is because that although cracks are easily generatedin the insulating layer at the boundary region where the wiring layer isformed, the influence of the generation of cracks can be efficientlyreduced.

Advantageous Effect of Invention

The substrate for suspension of the present invention takes effect ofrestraining the generation of cracks in the insulating layer at theboundary region between a region where a metal supporting substrateexists and a region where no metal supporting substrate exist. Also, thesubstrate for suspension of the present invention takes effect ofreducing the influence of cracks generated in the insulating layer atthe boundary region between a region where a metal supporting substrateexists and a region where no metal supporting substrate exist.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are each is a schematic diagram showing an example of ageneral substrate for suspension.

FIG. 2 is a schematic plan view showing the vicinity of a devicemounting area of a substrate for suspension according to a firstembodiment.

FIG. 3 is a schematic plan view showing the vicinity of a crossbar.

FIGS. 4A to 4C are each a sectional view along the line X-X of FIG. 3.

FIGS. 5A and 5B are each a schematic sectional view for explaining thesubstrate for suspension according to the first embodiment.

FIG. 6 is a schematic plan view for explaining a metal supportingsubstrate in the first embodiment.

FIGS. 7A and 7B are each a schematic plan view for explaining asubstrate for suspension according to a second embodiment.

FIGS. 8A to 8C are each a schematic sectional view for explaining thesubstrate for suspension according to the second embodiment.

FIGS. 9A and 9B are each a schematic plan view for explaining thesubstrate for suspension according to the second embodiment.

FIG. 10 is a schematic sectional view for explaining the substrate forsuspension according to the second embodiment.

FIGS. 11A and 11B are each a schematic plan view for explaining thesubstrate for suspension according to the second embodiment.

FIGS. 12A and 12B are each a schematic plan view for explaining thesubstrate for suspension according to the second embodiment.

FIGS. 13A and 13B are each a schematic diagram for explaining asubstrate for suspension according to a third embodiment.

FIGS. 14A and 14B are each a schematic diagram for explaining thesubstrate for suspension according to the third embodiment.

FIG. 15 is a schematic plan view for explaining the substrate forsuspension according to the third embodiment.

FIGS. 16A to 16E are a schematic sectional view showing an example of aproduction process of substrate for suspension according to the firstembodiment.

FIGS. 17A to 17D are a schematic sectional view showing another exampleof the production process of substrate for suspension according to thefirst embodiment.

FIGS. 18A to 18E are a schematic sectional view for explaining theeffect of the first embodiment.

FIGS. 19A to 19E are a schematic sectional view showing an example of aproduction process of substrate for suspension according to the thirdembodiment.

FIGS. 20A to 20D are a schematic sectional view showing another exampleof a production process of substrate for suspension according to thesecond embodiment.

FIGS. 21A to 21D are a schematic sectional view showing an example ofthe production process of substrate for suspension according to thethird embodiment.

DESCRIPTION OF EMBODIMENTS

A substrate for suspension and a production process of substrate forsuspension according to the present invention will be explained indetail.

A. Substrate for Suspension

First, the substrate for suspension of the present invention will beexplained. The substrate for suspension of the present invention may belargely classified into three embodiments.

1. First Embodiment

The substrate for suspension of a first embodiment comprises a metalsupporting substrate, an insulating layer formed on the metal supportingsubstrate, a wiring layer formed on the insulating layer, and a coverlayer formed to cover the wiring layer, wherein the substrate forsuspension comprises a first structural part including the metalsupporting substrate, the insulating layer, the wiring layer, and thecover layer, and a second structural part formed so as to extendcontinuously from the first structural part and has no metal supportingsubstrate, and wherein a position of an edge of the upper surface of theinsulating layer coincides with a position of an edge of a lower surfaceof the cover layer or the position of the edge of the upper surface ofthe insulating layer is positioned on a side closer to the wiring layerthan to the edge of the lower surface of the cover layer at a boundaryregion between the first structural part and the second structural part.

FIGS. 1A to 1B are each a schematic diagram showing an example of ageneral substrate for suspension. FIG. 1A is a schematic plan view of asubstrate for suspension, and FIG. 1B is a sectional view along the lineX-X of FIG. 1A. In FIG. 1A, the illustration of the cover layer isomitted for the sake of convenience. A substrate for suspension 100shown in FIG. 1A comprises a device mounting area 101 formed on one endthereof, an external circuit substrate connecting area 102 formed on theother end, and a plurality of wiring layers 103 a to 103 d thatelectrically connect the device mounting area 101 with the externalcircuit substrate connecting area 102. The wiring layer 103 a and thewiring layer 103 b are a pair of wiring layers and similarly, the wiringlayer 103 c and the wiring layer 103 d are also a pair of wiring layers.One of these two pairs of wiring layers is a writing wiring layer andthe other is a reading wiring layer. On the other hand, as shown in FIG.1B, the substrate for suspension has a metal supporting substrate 1, aninsulating layer 2 formed on the metal supporting substrate 1, a wiringlayer 3 formed on the insulating layer 2, and a cover layer 4 thatcovers the wiring layer 3.

FIG. 2 is a schematic plan view showing the vicinity of the devicemounting area of the substrate for suspension according to a firstembodiment. In FIG. 2, the illustration of the cover layer is omittedfor the sake of convenience, and the insulating layer and wiring layeron the upper half of the drawing are shown by the dotted line. The metalsupporting substrate 1 in FIG. 2 has a tongue section 11 mounting for adevice such as a magnetic hear slider (magnetic head mounted onread/write electrical circuit with suspension), an outrigger section 12positioned outside the tongue section 11, a crossbar 13 connecting thetongue section 11 with the outrigger section 12, and a base part 15supporting the bottom of the outrigger section 12. Moreover, in each ofthe areas A to D shown in FIG. 2, a first structural part including themetal supporting substrate 1, insulating layer 2, wiring layer 3, andcover layer (not shown) and a second structural part formed so as toextend continuously from the first structural part and has no metalsupporting substrate 1 are formed.

Also, in the first embodiment, as shown in FIG. 2, the wiring layer 3 ispreferably formed between the tongue section 11 and the outriggersection 12 in planar view. This is because that although cracks areeasily generated in the insulating layer under the wiring layer at theboundary region where the wiring layer is formed, the influence of thegeneration of cracks can be efficiently reduced. In Japanese PatentLaid-Open No. 2007-213793 mentioned above, it is disclosed that a wiringlayer is formed on the outrigger section. On the other hand, there aretechnologies in which the outrigger section is irradiated with a laserto adjust the pitch/roll angle of the gimbal. If these technologies areapplied to Japanese Patent Laid-Open No. 2007-213793, the wiring layeris easily deteriorated by the influence of the heat generated by laserradiation. Also, the stiffness of the wiring layer is a hindrance to theadjustment of the pitch/roll angle of the gimbal. For this reason, it ispreferable to arrange the wiring layer outside or inside the outriggersection. Here, if the wiring layer is arranged outside the outriggersection, an out-trace type substrate for suspension as shown in JapanesePatent Laid-Open No. 2007-287296 is obtained. There is the possibilitythat this out-trace type substrate for suspension has difficulty inflight-height control because the wiring layer is largely affected bythe wind pressure when a disk is rotated. Also, since no outriggersection exists outside the wiring layer, the wiring layer is susceptibleto a damage. As mentioned above, the wiring layer is preferably formedbetween the tongue section and the outrigger section in planar view fromthe viewpoint of preventing the wiring layer from being deteriorated bylaser radiation, from the viewpoint of reducing the influence of windpressure when a disk is rotated and from the viewpoint of preventing thewiring layer from being damaged.

On the other hand, FIG. 3 is a schematic plan view showing the vicinityof the crossbar. In FIG. 3, the wiring layer 3 is arranged so as tointersect the crossbar 13. There is the problem in that cracks 51 areeasily generated in the insulating layer 2 existing above the boundaryregion between a first structural part S₁ including the crossbar 13,insulating layer 2, wiring layer 3, and cover layer (not shown) whichare laminated in this order and a second structural part S₂ includingthe insulating layer 2, wiring layer 3, and cover layer (not shown) andno crossbar 13 which are laminated in this order. Examples of the reasonof the generation of cracks 51 include stress concentration on thesubstrate for suspension in use (for example, stress concentrationcaused by the oscillation of a device such as a magnetic head slider)and stress concentration on the substrate for suspension in production(for example, stress concentration caused by liquid treatment after thecrossbar 13 is formed and stress concentration when the substrate forsuspension is conveyed in the production stage). When cracks aregenerated and developed, it is assumed that the stress directly affectsthe wiring layer and the wiring layer is corroded or burn out in theworst case.

FIGS. 4A to 4C are each a sectional view along the line X-X in FIG. 3,showing a sectional view of the boundary region between the firststructural part S₁ and the second structural part S₂. When theinsulating layer in the first embodiment is formed, for example, by wetetching, the insulating layer usually has a trapezoidal shape insection.

The substrate for suspension of the first embodiment is primarilycharacterized by the feature that the position of the edge 2 a of theupper surface of the insulating layer 2 coincides with the position ofthe edge 4 a of the lower surface of the cover layer 4 (FIG. 4A) or ispositioned on the side (inner side) closer to the wiring layer 3 than tothe edge 4 a of the lower surface of the cover layer 4 (FIG. 4B) at theboundary region. The edge of the insulating layer 2 is reinforced andthe generation of cracks can be therefore restrained by that feature.Also, the insulating layer 2 is highly bonded with the cover layer 4 inusual from the viewpoint of securing the durability required for aproduct. Therefore, the infiltration of an etching solution between bothlayers can be prevented, the angle θ of the lower end section of theinsulating layer 2 can be increased, and the generation of cracks can berestrained also thanks to this point.

On the other hand, as shown in FIG. 4C, when the position of the upperend 2 a of the insulating layer 2 is on a considerably outer side of theedge of the lower surface 4 a of the cover layer 4, the edge of theinsulating layer 2 is not reinforced and therefore cracks are easilygenerated. Moreover, the insulating layer 2 is less bonded with theresist layer in the wet etching in usual. Therefore, an etching solutioninfiltrates between both layers, so that the angle θ of the lower endsection of the insulating layer 2 becomes small, and cracks are easilygenerated thanks to this point.

According to the first embodiment as mentioned above, the position ofthe edge of the upper surface of the insulating layer coincides with theposition of the edge of the lower surface of the cover layer or ispositioned on the side closer to the wiring layer than to the edge ofthe lower surface of the cover layer at the boundary region andtherefore, the generation of cracks in the insulating layer can berestrained. For this reason, the breaking of wire layer caused by stressconcentration can be prevented. Particularly, there is a recent need forthe development of a thin insulating layer and therefore, cracks areeasily generated in the insulating layer. However, according to thefirst embodiment, the generation of cracks can be efficiently restrainedin such a case.

With regard to the substrate for suspension of the first embodiment, themember and structure of the substrate for suspension will be explainedseparately.

(1) Member of the Substrate for Suspension

First, the member of the substrate for suspension of the firstembodiment will be explained. The substrate for suspension of the firstembodiment comprises a metal supporting substrate, an insulating layer,a wiring layer, and a cover layer.

The metal supporting substrate in the first embodiment functions as thesupport of the substrate for suspension. The material of the metalsupporting substrate is preferably a metal having spring properties.Specific examples of the material of the metal supporting substrate mayinclude SUS. Also, the thickness of the metal supporting substrate isfor example, in a range from 10 μm to 20 μm though it differs dependingon the type of material.

The insulating layer in the first embodiment is formed on the metalsupporting substrate. Although any material may be used as the materialof the insulating layer as long as it has insulating ability, resins aregiven as examples. Specific examples of the above resins may include apolyimide resin, polybenzoxazole resin, polybenzoimidazole resin,acrylic resin, polyether nitrile resin, polyether sulfone resin,polyethylene terephthalate resin, polyethylene naphthalate resin andpolyvinyl chloride resin. Among these resins, a polyimide resin ispreferable. This is because the polyimide resin is superior ininsulating ability, heat resistance and chemical resistance. Also, thematerial of the insulating layer may be either a photosensitive materialor non-photosensitive material. The thickness of the insulating layeris, for example, in a range from preferably 5 μm to 30 μm, morepreferably 5 μm to 18 μm and even more preferably 5 μm to 12 μm.

The wiring layer in the first embodiment is formed on the insulatinglayer. Although any material may be used as the wiring layer insofar asit has conductivity, examples of the material may include metals. Amongthese metals, copper (Cu) is preferable. Also, the material of thewiring layer may be rolled copper or electrolyte copper. The thicknessof the wiring layer is in a range from preferably 5 μm to 18 μm and morepreferably 9 μm to 12 μm. Also, a wiring plating section may be formedon the surface of apart of the wiring layer. This is because theformation of the wiring plating section can prevent the deterioration(for example, corrosion) of the wiring layer. Particularly, in the firstembodiment, this wiring plating section is preferably formed on theterminal section which connects with devices or an external circuitsubstrate. Although no particular limitation is imposed on the type ofthe wiring plating section, examples of the plating include Ni platingand Au plating. The thickness of the wiring plating section is within arange from 0.1 μm to 4.0 μm.

The cover layer in the first embodiment is formed so as to cover thewiring layer 3. The deterioration (for example, corrosion) of the wiringlayer can be prevented by the cover layer. Examples of the material ofthe cover layer may include resins exemplified as the material of theabove-mentioned insulating layer. Among these resins, a polyimide resinis preferable. Also, the material of the cover layer may be either aphotosensitive material or a non-photosensitive material. Also, thethickness of the cover layer is preferably in a range from 2 μm to 30 μmand more preferably in a range from 2 μm to 10 μm.

(2) Structure of the Substrate for Suspension

Next, the structure of the substrate for suspension of the firstembodiment will be explained. The substrate for suspension of the firstembodiment includes a first structural part including a metal supportingsubstrate, an insulating layer, a wiring layer and a cover layer whichare laminated in this order. As the wiring layer in the first structuralpart, a plurality of wiring layers having various functions may be used.Examples of the wiring layer include writing wiring layers, readingwiring layers, noise shielding wiring layers, crosstalk preventivewiring layers, power source wiring layers, ground wiring layers,flight-height control wiring layers, censor wiring layers, actuatorwiring layers, and heat assist wiring layers. Also, the substrate forsuspension of the first embodiment includes a second structural partformed so as to extend continuously from the first structural part andhas no metal supporting substrate. The second structural partcorresponds to, for example, a structural part obtained by removing onlythe metal supporting substrate from the first structural part.

Also, the substrate for suspension of the first embodiment ischaracterized by the feature that, as shown in FIG. 5A, the position ofthe edge 2 a of the upper surface of the insulating layer 2 coincideswith the position of the edge 4 a of the lower surface of the coverlayer 4 at the boundary region between the first structural part and thesecond structural part. The term “coincide” in the first embodimentmeans not only strict coincidence but also substantial coincidence. Theterm “substantial coincidence” means that the position of the edge 4 aof the lower surface of the cover layer 4 is positioned on the sidecloser to the wiring layer 3 than to the position of the edge 2 a of theupper surface of the insulating layer 2 and the width between both edgesis 10 μm or less (preferably 5 μm or less). When a resist pattern isused to form the insulating layer 2 as shown in FIGS. 16A to 16E whichwill be explained later, there is the case where a substrate forsuspension is obtained in which the edge 4 a of the lower surface of thecover layer 4 is positioned on the side closer to the wiring layer 3than to the edge 2 a of the upper surface of the insulating layer 2.Also, when the width between the edge 3 a of the lower surface of thewiring layer 3 and the edge 4 a of the lower surface of the cover layer4 is W₁, the value of W₁ is preferably 10 μm or more and more preferably15 μm or more. This is because that when the value of W₁ is too small,there is the possibility that the wiring layer 2 is exposed from thecover layer 4 by the relative slippage of the cover layer 4 to thewiring layer 3 when the cover layer 4 is formed on the wiring layer 3.The value of W₁ is preferably, for example, 30 μm or less and morepreferably 20 μm or less. This is because that when the value of W₁ istoo large, the entire width of the wiring section is wider, which bringsabout layout difficulty because of the space limit. Also, the angle θ ofthe lower end section of the insulating layer 2 is preferably 30 degreesor more, more preferably 40 degrees or more and even more preferably 50degrees or more.

Also, the substrate for suspension of the first embodiment ischaracterized by the feature that, as shown in FIG. 5B, the position ofthe edge 2 a of the upper surface of the insulating layer 2 ispositioned on the side closer to the wiring layer 3 than to the positionof the edge 4 a of the lower surface of the cover layer 4 at theboundary region between the first structural part and the secondstructural part. When the width from the edge 4 a of the lower surfaceof the cover layer 4 to the edge of 2 a of the upper surface of theinsulating layer 2 is W₂, the value of W₂ is preferably 15 μm or less,more preferably 10 μm or less and even more preferably 5 μm or less.This is because the generation of cracks can be restrained moreefficiently if the width is within the above range.

Also, in the first embodiment, the insulating layer and the cover layerare preferably made of the same material. This is because the adhesionbetween both layers is more improved. When the adhesion between bothlayers is high, the infiltration into both layers can be prevented, sothat the angle θ of the lower end section of the insulating layer can beincreased. As a result, the generation of cracks in the insulating layercan be restrained. The term “same material” in the first embodimentmeans materials having the same fundamental skeleton. Particularly, inthe first embodiment, the materials of the insulating layer and coverlayer are respectively preferably a polyimide resin. Moreover, thematerial of the cover layer is preferably a material having a loweretching rate for an etching solution than the material of the coverlayer.

Next, the boundary region in the first embodiment will be explained.There is no particular limitation to the boundary region as long as itis a region of the boundary between the aforementioned first structuralpart and second structural part. Examples of the boundary region mayinclude the regions A to D in the above FIG. 2. The region A in FIG. 2is shown in an embodiment including a crossbar 13 as the metalsupporting substrate of the first structural part. Both ends of thecrossbar 13 are boundaries between a region where the metal supportingsubstrate exists and a region where no metal supporting substrate exist.Particularly, the region A is largely affected by the oscillation ofdevices when the substrate for suspension is used. Therefore, the edgeof the upper surface of the insulating layer preferably coincides withthe edge of the lower surface of the cover layer or is positioned on theside closer to the wiring layer than to the edge of the lower surface ofthe cover layer in this boundary region. Moreover, since, among theregion A, the boundary region on the side closer to the tongue section11 is easily affected by distortion and the like, the edge of theposition of the upper surface of the insulating layer preferablycoincides with the edge of the lower surface of the cover layer or ispositioned on the side closer to the wiring layer than to the edge ofthe lower surface of the cover layer at the boundary region on the sidecloser to the tongue section 11.

Also, although particular limitation is not imposed on the position ofthe crossbar in the first embodiment as long as it is a position atwhich the tongue section and outrigger section can be connected witheach other, the crossbar is preferably formed on the end surface of thetongue section in the short-side direction of the substrate forsuspension. In the first embodiment, particularly, the crossbar 13 ispreferably formed so as to overlap on the substrate for suspension inthe short-side direction in the center 16 of oscillation of a device asshown in FIG. 6. This is because that the oscillation of the device canbe minimized, for example, in the generation of HDI (Head DiskInterface).

The region B in FIG. 2 is shown in an embodiment including a tracesupport tab 14 as the metal supporting substrate of the first structuralpart. Both ends of the trace support tab 14 are boundaries between aregion where the metal supporting substrate exists and a region where nometal supporting substrate exist. Similarly, the region C in FIG. 2 isshown in an embodiment including a base section 15 as the metalsupporting substrate of the first structural part, and the region D inFIG. 2 is shown in an embodiment including a tongue section as the metalsupporting substrate of the first structural part.

In the first embodiment, examples of devices mounted on a devicemounting area may include a magnetic head slider, actuator andsemiconductor. The above actuator may be those comprising a magnetichead or those comprising no magnetic head.

2. Second Embodiment

Next, a second embodiment of the substrate for suspension according tothe present invention will be explained. The substrate for suspension ofthe second embodiment comprises a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, and a cover layer formed to coverthe wiring layer, wherein the substrate for suspension comprises a firststructural part including the metal supporting substrate, the insulatinglayer, the wiring layer, and the cover layer, and a second structuralpart formed so as to extend continuously from the first structural partand has no metal supporting substrate, and wherein at least one of awidth from an edge of the wiring layer to an edge of the insulatinglayer and a width from the edge of the wiring layer to an edge of thecover layer be locally larger in planar view at a boundary regionbetween the first structural part and the second structural part.

FIGS. 7A and 7B are each a schematic plan view showing the vicinity ofthe crossbar like that of FIG. 3. In the substrate for suspension of thesecond embodiment, the width from the edge 31 of the wiring layer 3 tothe edge 21 of the insulating layer 2 is preferably locally larger inplanar view at the boundary region (FIG. 7A). Also, in the substrate forsuspension of the second embodiment, the width from the edge 31 of thewiring layer 3 to the edge 41 of the cover layer 4 is preferably locallylarge in planar view at the boundary region (FIG. 7B). Also, though notshown in the drawings, in the second embodiment, both of the width fromthe edge 31 of the wiring layer 3 to the edge 21 of the insulating layer2 and the width from the edge 31 of the wiring layer 3 to the edge 41 ofthe cover layer 4 are preferably locally large in planar view at theboundary region.

Also, in the second embodiment, the description “the width is locallylarge” may be defined as follows. Since the insulating layer is formedfor the purpose of insulating the wiring layer, it is basically formedcorresponding to the wiring pattern of the wiring layer. For thisreason, the base line of the insulating layer 2 can be easily identifiedas shown in FIG. 7A. This base line can be easily identified regardlessof whether it is a linear line or curved line. For this reason, if thewidth from the edge 31 to the edge 21 at the boundary region is largerthan the width from the edge 31 to the edge 21 on this base line, thedescription “the width is locally large” can be identified. This is thesame to the cover layer in FIG. 7B.

FIG. 8A is a sectional view along the line X-X of FIG. 7A. In FIG. 7A,the width from the edge 31 of the wiring layer 3 to the edge 21 of theinsulating layer 2 is locally large at the boundary region. On the otherhand, FIGS. 8B and 8C respectively correspond to a sectional view alongthe line X-X of FIG. 7B. In FIG. 8B, the width from the edge 31 of thewiring layer 3 to the edge 21 of the insulating layer 2 and width fromthe edge 31 of the wiring layer 3 to the edge 41 of the cover layer 4are locally large at the boundary region. In FIG. 8C, the width from theedge 31 of the wiring layer 3 to the edge 41 of the cover layer 4 islocally large at the boundary region. When the insulating layer in thesecond embodiment is formed, for example, by wet etching, the insulatinglayer usually has a trapezoidal shape in section.

According to the second embodiment as mentioned above, at least one ofthe width from the edge of the wiring layer to the edge of theinsulating layer and the width from the edge of the wiring layer to theedge of the cover layer in planar view at the boundary region is made tobe locally large and therefore, the influence of cracks generated in theinsulating layer can be reduced. For this reason, the wiring layer canbe, for example, prevented from being burned out by stressconcentration. Particularly, there is a recent need for the developmentof a thin insulating layer and therefore, cracks tend to be easilygenerated in the insulating layer. However, according to the secondembodiment, the influence of cracks can be efficiently reduced.

With regard to the substrate for suspension of the second embodiment,the member and structure of the substrate for suspension will beexplained separately.

(1) Member of the Substrate for Suspension

First, the member of the substrate for suspension of the secondembodiment will be explained. The substrate for suspension of the secondembodiment has a metal supporting substrate, an insulating layer, awiring layer, and a cover layer. These members are the same as thosedescribed in the aforementioned “1. First embodiment (1) Member of thesubstrate for suspension” and the explanations of these members aretherefore omitted here.

(2) Structure of the Substrate for Suspension

Next, the structure of the substrate for suspension of the secondembodiment will be explained. The first structural part and secondstructural part of the substrate for suspension in the second embodimentare the same as those described in the aforementioned “1. Firstembodiment (2) Structure of the substrate for suspension” and theexplanations of these structures are therefore omitted here.

Also, the substrate for suspension in the second embodiment ischaracterized by the feature that at least one of the width from theedge of the wiring layer to the edge of the insulating layer and thewidth from the edge of the wiring layer to the edge of the cover layeris locally large in planar view at the boundary region. As shown in FIG.9A, when the width from the base line of the insulating layer 2 to theedge 21 of the insulating layer 2 is W₁, the value of W₁ is preferably30 μm or more, more preferably 50 μm or more, and even more preferably70 μm or more. On the other hand, there is no particular restriction onthe upper limit of W. Though the explanations with reference to FIG. 9Aare furnished as to the case where the width from the edge 31 of thewiring layer 3 to the edge 21 of the insulating layer 2 is locallylarge, this is the same to the case where the width from the edge of thewiring layer to the edge of the cover layer is locally large.

Also, the influence of cracks generated in the insulating layer can alsobe reduced by entirely increasing the width from the edge 31 of thewiring layer 3 to the edge 21 of the insulating layer 2 over the wholerange of these edges as shown in FIG. 9B. Although not illustrated inthe drawing, the influence of cracks generated in the insulating layercan also be reduced by increasing the width from the edge of the wiringlayer to the edge of the cover layer over the whole range of theseedges. However, the adoption of this structure requires a space enoughto spare with many restrictions on design freedom.

Also, in the substrate for suspension of the second embodiment as shownin FIG. 8B, the width from the edge 31 of the wiring layer 3 to the edge21 of the insulating layer 2 and the width from the edge 31 of thewiring layer 3 to the edge 41 of the cover layer 41 are preferablylocally large at the boundary region. This is because that thedevelopment of cracks can be efficiently restrained in the laminatedparts of the insulating layer and cover layer by forming a projectedsection of the both. In this case, the position of the edge of theinsulating layer and the position of the edge of the cover layer maycoincide with each other. Though the both edges may be deviated fromeach other, they are preferably coincides with each other. This isbecause the generation of cracks can be intrinsically restrained. Theabove term “coincide” means that the position of the edge of the uppersurface of the insulating layer coincides with the position of the edgeof the lower surface of the cover layer. Also, the term “coincide” meansnot only strict coincidence but also substantial coincidence. The term“substantial coincidence” means that the width W₂ from the edge 4 a ofthe lower surface of the cover layer 4 to the edge 2 a of the uppersurface of the insulating layer 2 is 10 μm or less (preferably 5 μm orless) as shown in FIG. 10. In this case, the edge of the lower surfaceof the cover layer may be positioned either inside or outside the edgeof the upper surface of the insulating layer.

Also, in the case where the insulating layer is formed by wet etchingand the edge of the insulating layer is made to coincide with the edgeof the cover layer at the boundary region, the angle θ of the lower endsection of the insulating layer can be increased, and the generation ofcracks can be restrained. Generally, the insulating layer and the coverlayer are strongly bonded with each other from the viewpoint of securingthe durability required for a product. This can prevent an etchingsolution from infiltrating between both layers and therefore, the angleθ of the lower end section of the insulating layer can be increased. Thegeneration of cracks can be restrained by increasing the angle. In thesecond embodiment, the angle θ of the lower end section of theinsulating layer is preferably 30 degrees or more, more preferably 40degrees or more and even more preferably 50 degrees or more.

In the second embodiment, the insulating layer and the cover layer arepreferably made of the same type of material. This reason is the same asthat described in “1. First embodiment (2) Structure of the substratefor suspension” and is therefore omitted here.

The boundary region in the second embodiment is the same as that(boundary region with reference to FIG. 2) described in theaforementioned first embodiment. Particularly, the region A is largelyaffected by the oscillation of devices when the substrate for suspensionis used. Therefore, it is preferable that at least one of the width fromthe edge of the wiring layer to the edge of the insulating layer and thewidth from the edge of the wiring layer to the edge of the cover layeris locally large in planar view at the boundary region. Moreover, since,among the region A, the boundary region on the side closer to the tonguesection 11 is easily affected by distortion and the like, it ispreferable that at least one of the width from the edge of the wiringlayer to the edge of the insulating layer and the width from the edge ofthe wiring layer to the edge of the cover layer is locally larger at theboundary region on the side closer to the tongue section 11.

Also, though there is no particular limitation to the position of thecrossbar in the second embodiment insofar as the crossbar can connectwith the tongue section and outrigger section, the crossbar ispreferably formed on the end surface of the tongue section in thedirection of the short side of the substrate for suspension. This reasonis the same as that described in the above paragraph “1. Firstembodiment (2) Structure of the substrate for suspension” and theexplanations of this reason are omitted here.

Also, in the second embodiment, the insulating layer 2 is preferablyformed on the crossbar 13 such that the edge 21 thereof reaches thetongue section 11 as shown in FIG. 11A. Similarly, the insulating layer2 is preferably formed on the crossbar 13 such that the edge 21 thereofreaches the outrigger section 12. Also, the insulating layer 2 ispreferably formed on the support trace tab 14 such that the edge 21thereof reaches the outrigger section 12 as shown in FIG. 11B. This isbecause such a structure enables effective restriction of the generationof cracks. Though the explanations with reference to FIGS. 11A and 11Bare furnished as to the case where the width from the edge 31 of thewiring layer 3 to the edge 21 of the insulating layer 2 is locallylarge, this is the same to the case where the width from the edge of thewiring layer to the edge of the cover layer is locally large.

Also, in the second embodiment, a curved structural section ispreferably formed so as to include the boundary region in planar view onat least one of the insulating layer and the cover layer. This isbecause that the existence of the curved structural section allows thedispersion of stress, thereby enabling further restriction on thegeneration of cracks in the insulating layer at the boundary region.Examples of the curved structural section may include a curvedstructural section formed at the tip of the projected section of theinsulating layer 2 as shown in FIG. 12A and a curved structural sectionformed so as to extend continuously from the base line of the insulatinglayer 2 as shown in FIG. 12B. The cover layer 4 may be formed with thesame curved structural section although not illustrated in FIGS. 12A and12B.

Also, the devices mounted on the device mounting area in the secondembodiment are the same as those described in the above paragraph “1.First embodiment (2) Structure of the substrate for suspension” andexplanations of these devices are omitted here. Other items are alsobasically the same as those described in the first embodiment.

3. Third Embodiment

Next, a third embodiment of the substrate for suspension according tothe present invention will be explained. The substrate for suspension ofthe third embodiment comprises a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, and a cover layer formed to coverthe wiring layer, wherein the substrate for suspension comprises a firststructural part including the metal supporting substrate, the insulatinglayer, the wiring layer and the cover layer, and a second structuralpart formed so as to extend continuously from the first structural partand has no metal supporting substrate, and wherein an auxiliary wiringlayer is formed between an edge of the wiring layer and an edge of theinsulating layer in planar view at a boundary region between the firststructural part and the second structural part.

FIGS. 13A and 13B are each a schematic diagram showing an example of thesubstrate for suspension of the third embodiment. FIG. 13A is aschematic plan view showing the vicinity of the crossbar like FIG. 7Aand FIG. 13B is a sectional view along the line X-X of FIG. 13A. Thesubstrate for suspension of the third embodiment is characterized by thefeature that the auxiliary wiring layer 7 is formed between the edge 31of the wiring layer 3 and the edge 21 of the insulating layer 2 inplanar view at the boundary region.

As mentioned above, according to the third embodiment, the auxiliarywiring layer is formed between the edge of the wiring layer and the edgeof the insulating layer in planar view at the boundary region andtherefore, the influence of cracks generated in the insulating layer canbe reduced. Therefore, the wiring layer can be, for example, preventedfrom being burned out by stress concentration. Particularly, there is arecent need for the development of a thin insulating layer andtherefore, cracks tend to be easily generated in the insulating layer.However, according to the third embodiment, the influence of cracks canbe efficiently reduced.

With regard to the substrate for suspension of the third embodiment, themember and structure of the substrate for suspension will be explainedseparately.

(1) Member of the Substrate for Suspension

First, the member of the substrate for suspension of the thirdembodiment will be explained. The substrate for suspension of the thirdembodiment has a metal supporting substrate, an insulating layer, awiring layer, and a cover layer. These members are the same as thosedescribed in the aforementioned “1. First embodiment (1) Member of thesubstrate for suspension” and the explanations of these members aretherefore omitted here.

Also, the substrate for suspension of the third embodiment has anauxiliary wiring layer. Although the auxiliary wiring layer may beconstituted of a material which may be either the same as or differentfrom that of the wiring layer, the former is preferable. This is becausethe auxiliary wiring layer can be formed at the same time as the wiringlayer is formed.

(2) Structure of the Substrate for Suspension

Next, the structure of the substrate for suspension of the thirdembodiment will be explained. The substrate for suspension of the thirdembodiment is largely characterized by the feature that the auxiliarywiring layer is formed between the edge of the wiring layer and the edgeof the insulating layer in planar view at the boundary region.

When, as shown in FIG. 13A, the width of the auxiliary wiring layer isW₃, the value of W₃ is preferably in a range from 10 μm to 50 μm, morepreferably in a range from 15 μm to 30 μm and even more preferably in arange from 15 μm to 20 μm. This is because when the value of W₃ is toosmall, there is the possibility that the progress of cracks can beinsufficiently restrained, whereas when the value of W₃ is too large,there are many restrictions on design freedom.

In the third embodiment, the position of the edge of the insulatinglayer preferably coincides with the position of the edge of the coverlayer as shown in FIG. 13B. This is because the generation of cracks canbe intrinsically restrained. The definition of the above term “coincide”is the same as that described in the above paragraph “2. Secondembodiment” and the explanations of the definition are omitted.

No particular limitation is imposed on the position where the auxiliarywiring layer is formed as long as it is positioned between the edge ofthe wiring layer (outermost wiring layer) and the edge of the insulatinglayer. Particularly, in the third embodiment, it is preferable that thesurface of the auxiliary wiring layer 7 is covered with the cover layer4 as shown in FIG. 13B. This is because the auxiliary wiring layer 7 canbe prevented from being deteriorated (for example, corroded).

Also, as shown in FIG. 14A, the edge 71 of the auxiliary wiring layer 7may coincide with the edge 21 of the insulating layer 2. If theycoincide with each other, the generation of cracks can be intrinsicallyrestrained. The above term “coincide” means that the edge of theposition of the upper surface of the insulating layer coincides with theposition of the edge of the lower surface of the auxiliary wiring layer.Also, the term “coincide” means not only strict coincidence but alsosubstantial coincidence. The term “substantial coincidence” means thatthe width from the edge of the lower surface of the auxiliary wiringlayer to the edge of the upper surface of the insulating layer is 10 μmor less (preferably 5 μm or less). In this case, the edge of the lowersurface of the auxiliary wiring layer may be positioned either inside oroutside the edge of the upper surface of the insulating layer.

Also, in the case where the insulating layer is formed by wet etchingand the edge of the insulating layer is made to coincide with the edgeof the auxiliary wiring layer at the boundary region, the angle θ of thelower end section of the insulating layer can be increased, and thegeneration of cracks can be restrained. Generally, the insulating layerand the auxiliary wiring layer are strongly bonded with each other. Thisprevents an etching solution from infiltrating between both layers andtherefore, the angle θ of the insulating layer can be increased. Thegeneration of cracks can be restrained by increasing the angle. Theangle θ of the lower end section of the insulating layer formed belowthe auxiliary wiring layer is for example, preferably 30 degrees ormore, more preferably 40 degrees or more and even more preferably 50degrees or more.

When the edge 71 of the auxiliary wiring layer 7 coincides with the edge21 of the insulating layer 2 as shown in FIG. 14A, a wiring platingsection 6 is preferably formed on the surface of the auxiliary wiringlayer 7 as shown in FIG. 14B. This is because the auxiliary wiring layercan be prevented from being deteriorated (for example, corroded). Inthis case, if the auxiliary wiring layer is formed of material havinghigh corrosion resistance, it is unnecessary to particularly form thewiring plating section. As examples of a method of forming the wiringplating section, a method may be, though not shown, given in which a viaportion which penetrates through the insulating layer to connect theauxiliary wiring layer electrically with the metal supporting substrateand electricity is supplied to the auxiliary wiring layer from the metalsupport substrate and via portion to form a wiring plating section bythe electrolytic plating method. Also, the wiring plating section may beformed by the electroless plating method.

Also, the substrate for suspension of the third embodiment may have thecharacteristics of the substrate for suspension of the secondembodiment. Specifically, an auxiliary wiring layer is formed betweenthe edge of the wiring layer and the edge of the insulating layer inplanar view at the boundary region, and further, at least one of thewidth from the edge of the wiring layer to the edge of the insulatinglayer and the width from the edge of the wiring layer to the edge of thecover layer may be locally larger. As an example, as shown in FIG. 15, asubstrate for suspension may be given in which an auxiliary wiring layer7 is formed between the edge 31 of the wiring layer 3 and the edge 21 ofthe insulating layer 2 and further, the width from the edge 31 of thewiring layer 3 to the edge 21 of the insulating layer 2 is locally largein planar view. Other things are also basically the same as thosedescribed in the first or second embodiment.

B. Production Process of Substrate for Suspension

Next, a production process of substrate for suspension according to thepresent invention will be explained. The production process of substratefor suspension according to the present invention may be largelyclassified into three embodiments.

1. First Embodiment

In this first embodiment, there is provided a production process ofsubstrate for suspension comprises: a metal supporting substrate, aninsulating layer formed on the metal supporting substrate, a wiringlayer formed on the insulating layer, and a cover layer formed to coverthe wiring layer, a first structural part including the metal supportingsubstrate, the insulating layer, the wiring layer, and the cover layer,and a second structural part formed so as to extend continuously fromthe first structural part and has no metal supporting substrate, themethod comprises a step of: forming the insulating layer by carrying outwet etching such that a position of an edge of an upper surface of theinsulating layer coincides with a position of an edge of a lower surfaceof the cover layer or the position of the edge of the upper surface ofthe insulating layer is positioned on a side closer to the wiring layerthan to the position of the edge of the lower surface of the cover layerat a boundary region between the first structural part and the secondstructural part.

FIGS. 16A to 16E are a schematic sectional view showing an example ofthe production process of substrate for suspension according to thefirst embodiment. Similar to FIGS. 4A to 4C, FIGS. 16A to 16E correspondto the sectional view along the line X-X of FIG. 3. In FIGS. 16A to 16E,first, a laminate member is prepared and the laminated member has ametal supporting member 1X, an insulating member 2X formed on the metalsupporting member 1X and a conductive member 3X formed on the insulatingmember 2X (FIG. 16A). Next, a prescribed resist pattern (patternedresist layer) is formed on the surface of the conductive member 3X byusing a dry film resist (DFR) and the conductive member 3X exposed fromthe resist pattern is wet-etched to form a wiring layer 3 (FIG. 16B). Atthis time, the same resist pattern may be formed on the surface of themetal supporting member 1X and a jig hole and the like may be formed atthe same time when the above wet etching is carried out.

After that, a cover layer 4 is formed in to cover the wiring layer 3(FIG. 16C). Then, a resist pattern 5 is formed so as to cover the coverlayer 4 by using DFR (FIG. 16D). At this time, the width W₃ from theedge of the lower surface of the cover layer 4 to the edge of the lowersurface of the resist pattern 5 is preferably, for example, 10 μm orless and more preferably in a range from 4 μm to 6 μm. When the value ofW₃ is too large, there is a tendency that an area where an etchingsolution infiltrates into the boundary between the insulating layer 2and the resist pattern 5 is widened and the angle θ of the lower endsection of the insulating layer 2 is decreased. Then, the insulatingmember 2X exposed from the resist pattern 5 is wet-etched to form aninsulating layer 2 (FIG. 16E). The production process of substrate forsuspension in the first embodiment is characterized by the feature thatthe edge 2 a of the upper surface of the insulating layer 2 coincideswith the edge 4 a of the lower surface of the cover layer 4 or ispositioned on the side closer to the wiring layer 3 than to the edge 4 aof the lower surface of the cover layer 4. In FIG. 16E, the processingof the outline of the metal supporting member 1X is carried out by wetetching to form a metal supporting substrate 1.

FIGS. 17A and 17D are each a schematic sectional view showing anotherexample of the production process of substrate for suspension accordingto the first embodiment. Although the production process illustrated inFIGS. 17A to 17D is basically the same as the production processillustrated in FIGS. 16A to 16E. In FIG. 17C, the resist pattern is notformed using DFR or the like and the insulating member 2X is wet-etchedby using the cover layer 4 as the resist layer.

As mentioned above, according to the first embodiment, the insulatinglayer is formed by carrying out wet etching in such a manner that theposition of the edge of the upper surface of the insulating layercoincides with the position of the edge of the lower surface of thecover layer or is positioned on the side closer to the wiring layer thanto the edge of the lower surface of the cover layer. This ensures thatthe substrate for suspension which restrains the generation of cracks inthe insulating layer can be obtained. Also, the insulating layer andcover layer in the first embodiment are highly adhesive to each otherfrom the viewpoint of securing the durability required for a product. Itis therefore possible to prevent an etching solution from infiltratinginto a space between both layers and the angle θ of the lower endsection of the insulating layer can be increased, and the generation ofcracks can be restrained from this also.

If edge 2 a of the upper surface of the insulating layer 2 is positionedon a considerably outer side of the edge 4 a of the lower surface of thecover layer 4 as shown in FIGS. 18A to 18E (FIG. 18E), the edge of theinsulating layer 2 is not reinforced and therefore cracks are easilygenerated. Moreover, the insulating layer 2 is less bonded with theresist pattern 5 in usual as shown in FIG. 18D. Therefore, an etchingsolution infiltrates in a space between both layers, so that the angle θof the lower end section of the insulating layer 2 becomes small, andcracks are easily generated due to this point. When a solvent typephotoresist or alkali developing peelable type photoresist is used forthe resist layer in the formation of the insulating layer, particularlyan alkali type etching solution which is usually used as an etchingsolution for a polyimide resin may dissolve the resist layer, causingdeterioration in the adhesion between the insulating layer and theresist layer. Then, the etching solution infiltrates into a spacebetween the insulating layer and the resist layer to etch the insulatinglayer at a part into which the etching solution infiltrates, and as theresult, the insulating layer has a conspicuous taper shape.

Also, no particular limitation is imposed on the production process ofsubstrate for suspension in the first embodiment insofar as the methodinvolves the insulating layer formation step. As an example of theproduction process of substrate for suspension in the first embodiment,each step shown in FIGS. 16 and 17 will be explained.

(1) Laminate Member Preparation Step

The laminate member preparation step in the first embodiment is a stepof preparing a laminate member provided with a metal supporting member,an insulating member formed on the metal supporting member and aconductive member formed on the insulating member. As the laminatemember in the first embodiment, a commercially available laminate membermay be used or the laminate member may also be formed by forming aninsulating member and a conductive member on a metal supporting member.

(2) Wiring Layer Formation Step

The wiring layer formation step in the first embodiment is a step offorming a wiring layer by forming a resist pattern on the conductivemember of the laminate member and by wet-etching the conductive memberexposed from the resist pattern. The type of etching solution used inthe wet etching is preferably selected corresponding to the type ofconductive member. When the material of the conductive member is, forexample, copper, an iron chloride type etching solution or the like maybe used. Also, when other layers are etched by the above etchingsolution, it is preferable to form a resist protecting these otherlayers from the etching solution according to the need.

(3) Cover Layer Formation Step

The cover layer formation step in the first embodiment is a step offorming a cover layer covering the wiring layer. No particularlimitation is imposed on the method of forming a cover layer and it ispreferable to select an appropriate method corresponding to the type ofcover layer. When the material of the cover layer is a photosensitivematerial, the cover layer formed on the entire surface is exposed tolight to obtain a patterned cover layer. When the material of the coverlayer is a non-photosensitive material, a prescribed resist pattern isformed on the surface of the cover layer formed on the entire surfaceand the part exposed from the resist pattern is removed by wet etchingto thereby obtain a patterned cover layer.

(4) Insulating Layer Formation Step

The insulating layer formation step in the first embodiment is a step offorming an insulating layer by carrying out wet etching in such a mannerthat the position of the edge of the upper surface of the insulatinglayer coincides with the position of the edge of the lower surface ofthe cover layer or is positioned on the side closer to the wiring layerthan to the edge of the lower surface of the cover layer at the boundaryregion between the first structural part and the second structural part.

It is preferable that the type of etching solution to be used in the wetetching is properly selected corresponding to the type of insulatinglayer. When the material of the insulating layer is, for example, apolyimide resin, an alkali type etching solution or the like may beused.

In the first embodiment, the cover layer is preferably used as a resistlayer in the insulating layer formation step. This is because it isunnecessary to form a resist layer separately. Moreover, the adhesionbetween the insulating layer and the cover layer is made to be high inusual from the viewpoint of securing the durability required for aproduct. Therefore, the infiltration of an etching solution between bothlayers can be prevented, and the angle θ of the lower end section of theinsulating layer can be increased. When the cover layer is used as theresist layer, the material of the cover layer is preferably a materialhaving a lower etching rate for the etching solution than the materialof the wiring layer. This is because such a material is useful for theresist layer. Even in the case where the etching rate of the material ofthe cover layer is the same as or higher than that of the material ofthe wiring layer, the cover layer can be used as the resist layer if thethickness of the cover layer can be secured sufficiently, for example.

Also, it is unnecessary to use the cover layer as the resist layer. Inthis case, it is necessary to form a resist layer separately to coverthe cover layer. However, this has the advantage that the material canbe selected in a wide range of materials because it is unnecessary totake the etching rate of the material of the cover layer intoconsideration.

(5) Metal Supporting Substrate Formation Step

The metal supporting substrate formation step in the first embodiment isa step of forming a metal supporting substrate by wet-etching the metalsupporting member. Generally, in this step, outline processing of themetal supporting member is carried out. The type of etching solutionused in the wet etching is preferably selected according to the type ofmetal supporting member. When the material of the metal supportingmember is SUS, an iron chloride type etching solution or the like may beused. Also, when other layers are etched by the above etching solution,it is preferable to form a resist protecting these other layers from theetching solution according to the need.

(6) Other Steps

The production process of substrate for suspension according to thefirst embodiment may involve, besides the above steps, a wiring platingsection formation step of forming a wiring plating section at a part ofthe wiring layer. The method of forming a wiring plating section ispreferably the electrolytic plating method though it may be theelectrolytic plating method or electroless plating method. Theproduction process of substrate for suspension according to the firstembodiment may involve a via section formation step of forming a viaportion which penetrates through the insulating layer and connects thewiring layer electrically with the metal supporting substrate. Examplesof a method of forming the via portion may include the plating methods(electrolytic plating method and electroless plating method).

2. Second Embodiment

Next, a second embodiment of the production process of substrate forsuspension according to the present invention will be explained. In thissecond embodiment, there is provided a production process of substratefor suspension comprising: a metal supporting substrate, an insulatinglayer formed on the metal supporting substrate, a wiring layer formed onthe insulating layer, and a cover layer formed to cover the wiringlayer, a first structural part including the metal supporting substrate,the insulating layer, the wiring layer, and the cover layer, and asecond structural part formed so as to extend continuously from thefirst structural part and has no metal supporting substrate, the methodcomprises a step of: forming at least one of the insulating layer andthe cover layer such that at least one of a width from an edge of thewiring layer to an edge of the insulating layer and a width from theedge of the wiring layer to an edge of the cover layer is locally largein planar view at a boundary region between the first structural partand the second structural part.

FIGS. 19A to 19E are a schematic sectional view showing an example ofthe production process of substrate for suspension according to thesecond embodiment. Similar to FIG. 8A, FIGS. 19A to 19E correspond tothe sectional view along the line X-X of FIG. 7A. In FIGS. 19A to 19E,first, a laminate member is prepared which has a metal supporting member1X, an insulating member 2X formed on the metal supporting member 1X,and a conductive member 3X formed on the insulating member 2X (FIG.19A). Next, a prescribed resist pattern (patterned resist layer) isformed on the surface of the conductive member 3X by using a dry filmresist (DFR) and the conductive member 3X exposed from the resistpattern is wet-etched to form a wiring layer 3 (FIG. 19B). At this time,the same resist pattern may be formed on the surface of the metalsupporting member 1X and a jig hole and the like may be formed at thesame time when the above wet etching is carried out.

After that, a cover layer 4 is formed to cover the wiring layer 3 (FIG.19C). Then, a resist pattern 5 is formed so as to cover the cover layer4 by using DFR (FIG. 19D). Then, the insulating member 2X exposed fromthe resist pattern 5 is wet-etched to form an insulating layer 2 (FIG.195). The production process of substrate for suspension in the secondembodiment is characterized by the feature that the insulating layer 2is formed such that the width from the edge 31 of the wiring layer 3 tothe edge 21 of the insulating layer 2 is made be locally large in thiswet etching. In FIG. 19E, the processing of the outline of the metalsupporting member 1X is carried out by wet etching to form a metalsupporting substrate 1.

FIGS. 20A to 20D are a schematic sectional view showing another exampleof the production process of substrate for suspension according to thesecond embodiment. Similar to FIG. 8B, FIGS. 20A to 20D correspond tothe sectional view along the line X-X of FIG. 7B. Although theproduction process illustrated in FIGS. 20A to 201D is basically thesame as that illustrated in FIGS. 19A to 19E, the resist pattern is notformed by DFR or the like and the insulating member 2X is wet etchedusing the cover layer 4 as the resist layer in FIG. 20C. This enableseasy production of the substrate for suspension in which the edge 21 ofthe insulating layer 2 coincides with the edge 41 of the cover layer 4.

As an example of the production process of substrate for suspension asshown in FIG. 8C, the additive method may be given. In the additivemethod, first, a patterned insulating layer 2 is formed on the surfaceof a metal supporting substrate 1. Then, a resist pattern is formed onthe insulating layer 2 and a wiring layer 3 is formed on the insulatinglayer exposed from the resist pattern by the plating method. Then, thecover layer 4 may be formed such that the width from the edge 31 of thewiring layer 3 to the edge 41 of the cover layer 4 is locally large.

According to the second embodiment as mentioned above, the substrate forsuspension with reduced influence of cracks generated in the insulatinglayer can be obtained by forming at least one of the insulating layerand the cover layer such that at least one of the width from the edge ofthe wiring layer to the edge of the insulating layer and the width fromthe edge of the wiring layer to the edge of the cover layer is locallylarge in planar view at the boundary region.

No particular limitation is imposed on the production process ofsubstrate for suspension according to the second embodiment insofar asthe method involves a step of forming at least one of the insulatinglayer and the cover layer in the above specified configuration. Eachstep illustrated in the above FIGS. 19 and 20 will be explained as anexample of the production process of substrate for suspension in thesecond embodiment.

(1) Laminate Member Preparation Step

The laminate member preparation step in the second embodiment is thesame as that described in the above paragraph “B. Production process ofsubstrate for suspension 1. First embodiment”, and therefore, theexplanation of the step is omitted here.

(2) Wiring Layer Formation Step

The wiring layer formation step in the second embodiment is the same asthat described in the above paragraph “B. Production process ofsubstrate for suspension 1. First embodiment”, and therefore, theexplanation of the step is omitted here.

(3) Cover Layer Formation Step

The cover layer formation step in the second embodiment is the same asthat described in the above paragraph “B. Production process ofsubstrate for suspension 1. First embodiment”, and therefore, theexplanation of the step is omitted here.

(4) Insulating Layer Formation Step

The insulating layer formation step in the second embodiment is a stepof forming an insulating layer by wet-etching the above insulatingmember.

It is preferable that the type of etching solution used for the wetetching is properly selected according to the type of insulating layer.When the material of the insulating layer is, for example, a polyimideresin, an alkali type etching solution or the like may be used.

In the second embodiment, the cover layer is preferably used as theresist layer in the insulating layer formation step. This reason is thesame as that described in the above paragraph “B. Production process ofsubstrate for suspension 1. First embodiment”, and therefore, theexplanation of this reason is omitted here.

In the second embodiment, it is unnecessary to use the cover layer asthe resist layer. In this case, it is necessary to form a resist layerseparately to cover the cover layer. However, this has the advantagethat the material can be selected in a wide range of materials becauseit is unnecessary to take the etching rate of the material of the coverlayer into consideration.

Also, when a solvent type photoresist or alkali developing peelable typephotoresist is used for the resist layer in the formation of theinsulating layer, particularly an alkali type etching solution which isusually used as an etching solution for a polyimide resin may dissolvethe resist layer, causing deterioration in the adhesion between theinsulating layer and the resist layer. Due to that, the etching solutioninfiltrates between the insulating layer and the resist layer to etchthe insulating layer at a part into which the etching solutioninfiltrates, and as the result, the insulating layer exhibits aconspicuous taper shape.

In the second embodiment, particularly, it is preferable to form theinsulating layer and the cover layer such that the position of the edgeof the insulating layer coincides with the position of the edge of thecover layer at the above boundary region. This is because the generationof cracks can be intrinsically restrained.

(5) Metal Supporting Substrate Formation Step

The metal supporting substrate formation step in the second embodimentis the same as that described in the above paragraph “B. Productionprocess of substrate for suspension 1. First embodiment”, and therefore,the explanation of the step is omitted here.

(6) Other Steps

The production process of substrate for suspension according to thesecond embodiment may involve, besides the above steps, a wiring platingsection formation step of forming a wiring plating section at a part ofthe wiring layer. The production process of substrate for suspensionaccording to the second embodiment may involve a via section formationstep of forming a via portion which penetrates through the insulatinglayer and connects the wiring layer electrically with the metalsupporting substrate. These steps are the same as those described in theabove paragraph “B. Production process of substrate for suspension 1.First embodiment”, and therefore, the explanation of these steps areomitted here.

3. Third Embodiment

Next, a third embodiment of the production process of substrate forsuspension according to the present invention will be explained. Theproduction process of substrate for suspension in the third embodimentis a production process of substrate for suspension comprises: a metalsupporting substrate, an insulating layer formed on the metal supportingsubstrate, a wiring layer formed on the insulating layer, and a coverlayer formed to cover the wiring layer, a first structural partincluding the metal supporting substrate, the insulating layer, thewiring layer, and the cover layer, and a second structural part formedso as to extend continuously from the first structural part and has nometal supporting substrate, the method comprises a step of: a wiringlayer formation step of forming an auxiliary wiring layer between anedge of the wiring layer and an edge of the insulating layer in planarview at a boundary region between the first structural part and thesecond structural part.

FIGS. 21A to 21D are a schematic sectional view showing an example ofthe production process of substrate for suspension in the thirdembodiment. Similar to FIG. 13B, FIGS. 21A to 21D correspond to thesectional view along the line X-X of FIG. 13A. Though the productionprocess illustrated in FIGS. 21A to 21D are basically the same as theproduction process illustrated in FIGS. 19A to 19E, an auxiliary wiringlayer 7 is formed at the same time when the wiring layer 3 is formed inFIG. 21B. Although the cover layer 4 is used as the resist layer in FIG.21C, a resist pattern may be separately formed by using DFR or the like.The auxiliary wiring layer 7 may be used as the resist layer in the caseof obtaining a substrate for suspension as shown in FIG. 14A.

According to the above third embodiment, as mentioned above, anauxiliary wiring layer is formed between the edge of the wiring layerand the edge of the insulating layer at the boundary region andtherefore, a substrate for suspension with reduced influence of cracksgenerated in the insulating layer can be obtained.

No particular limitation is imposed on the production process ofsubstrate for suspension in the third embodiment insofar as the methodinvolves a wiring layer formation step of forming an auxiliary wiringlayer. Although the auxiliary wiring layer and other wiring layers maybe formed either simultaneously or in separate steps, the former ispreferable. This is because the production process can be simplified.Also, each step in the production process of substrate for suspension inthe third embodiment is the same as that in the above paragraph “B.Production process of substrate for suspension 2. Second embodiment”,and therefore, the explanation of the step is omitted here

The present invention is not limited to the aforementioned embodiments.These embodiments are examples and whatever has substantially the samestructure and produces the same action effect as the technical spiritdescribed in the claim of the present invention is embraced by thetechnical scope of the present invention.

EXAMPLES

The present invention will be explained in more detail by way ofexamples.

Example 1

A laminate member comprising 18-μm-thick SUS 304 (metal supportingmember), a 10-μm-thick polyimide resin layer (insulating member) and a9-μm-thick electrolytic copper layer (conductive member) was prepared(FIG. 16A). Then, resist patterns were simultaneously formed on bothsurfaces of the laminate member by patterning using a dry film resist insuch a manner as to form a jig hole for which positional accuracy wasimportant on the SUS side and a wiring layer on the electrolytic copperside. Then, etching was carried out using a ferric chloride solution,followed by peeling of the resist (FIG. 16B).

Next, the surface of the patterned wiring layer was coated with apolyimide precursor solution by a die coater and the coating film wasdried. Then, a resist pattern was formed, and developed while thepolyimide precursor film was etched at the same time. Then, theresulting film was heated under a nitrogen atmosphere to cure(imidization) to form a cover layer (FIG. 16C). The cover layer wasformed in such a way as to cover the wiring layer. The thickness of thecover layer formed on the wiring layer was 5 μm.

Then a resist pattern was formed to form an insulating member bypatterning and the exposed part of the polyimide resin was removed bywet etching (FIG. 16D). At this time, W₃ in FIG. 16D was 5 μm. The edgeof the upper surface of the insulating layer was made to coincide withthe edge of the lower surface of the cover layer by this wet etching.Finally, a resist pattern was formed to carry out the processing of theoutline of the metal supporting member and the exposed part of SUS wasremoved by wet etching to obtain a substrate for suspension (FIG. 16E).The angle θ of the lower end section of the insulating layer was 50degrees.

Example 2

A substrate for suspension was obtained in the same manner as in Example1 except that a polyimide resin having a lower etching rate than thepolyimide resin which was the insulating member was used as the materialof the cover layer and the cover layer was used as the resist (see FIGS.17A to 17D). The angle θ of the lower end section of the insulatinglayer was 60 degrees.

Example 3

A laminate member comprising 18-μm-thick SUS 304 (metal supportingmember), a 10-μm-thick polyimide resin layer (insulating member) and a9-μm-thick electrolytic copper layer (conductive member) was prepared(FIG. 19A). Then, resist patterns were simultaneously formed on bothsurfaces of the laminate member by patterning using a dry film resist insuch a manner as to form a jig hole for which positional accuracy wasimportant on the SUS side and a wiring layer on the electrolytic copperside. Then, etching was carried out using a ferric chloride solution,followed by peeling of the resist (FIG. 19B).

Next, the surface of the patterned wiring layer was coated with apolyimide precursor solution by a die coater and the coating film wasdried. Then, a resist pattern was formed, and developed while thepolyimide precursor film was etched at the same time. Then, theresulting film was heated under a nitrogen atmosphere to cure(imidization) to form a cover layer (FIG. 19C). The cover layer wasformed in such a way as to cover the wiring layer. The thickness of thecover layer formed on the wiring layer was 5 μm.

Then, a resist pattern was formed to form an insulating member bypatterning and the exposed part of the polyimide resin was removed bywet etching (FIG. 19D). Finally, a resist pattern was formed to carryout the processing the outline of the metal supporting member and theexposed part of SUS was removed by wet etching to obtain a substrate forsuspension (FIG. 19E). The width W₁ (see FIG. 9A) from the base line ofthe insulating layer 2 to the edge 21 of the insulating layer 2 was 80μm.

Example 4

A substrate for suspension was obtained in the same manner as in Example3 except that a polyimide resin having a lower etching rate than thepolyimide resin which was the insulating member was used as the materialof the cover layer and the cover layer was used as the resist (see FIGS.20A to 20D).

Example 5

A laminate member comprising 18-μm-thick SUS 304 (metal supportingmember), a 10-μm-thick polyimide resin layer (insulating member) and a9-μm-thick electrolytic copper layer (conductive member) was prepared(FIG. 21A). Then, resist patterns were simultaneously formed on bothsurfaces of the laminate member by patterning using a dry film resist insuch a manner as to form a jig hole for which positional accuracy wasimportant on the SUS side and a wiring layer and an auxiliary wiringlayer on the electrolytic copper side. Then, etching was carried outusing a ferric chloride solution, followed by peeling of the resist(FIG. 21B). The width W₃ of the auxiliary wiring layer 7 (see FIG. 13A)was 20 μm.

Next, the surface of the patterned wiring layer was coated with apolyimide precursor solution by a die coater and the coating film wasdried. Then, a resist pattern was formed, and developed while thepolyimide precursor film was etched. Then, the resulting film was heatedunder a nitrogen atmosphere to cure (imidization) to form a cover layer(FIG. 21C). The cover layer was formed in such a way as to cover thewiring layer. The thickness of the cover layer formed on the wiringlayer was 10 μm. As the material of the cover layer, a polyimide resinwas used which had a lower etching rate than the polyimide resin whichwas the insulating member.

Then, the exposed part of the polyimide resin was removed by wet etchingusing the cover layer as the resist layer. Finally, a resist pattern wasformed to carry out the processing of the outline of the metalsupporting member and the exposed part of SUS was removed by wet etchingto obtain a substrate for suspension (FIG. 21D).

REFERENCE SIGNS LIST

1: Metal supporting substrate, 2: Insulating layer, 2 a: Upper end ofinsulating layer, 3: Wiring layer, 4: Cover layer, 4 a: Lower end ofCover layer, 5: Resist layer (resist pattern), 6: Wiring platingsection, 7: Auxiliary wiring layer, 11: Tongue section, 12: Outriggersection, 13: Crossbar, 14: Trace support tab, 15: Base section, 16:Oscillation center, 51: Crack

The invention claimed is:
 1. A substrate for suspension comprising ametal supporting substrate, an insulating layer formed on the metalsupporting substrate, a wiring layer formed on the insulating layer, anda cover layer formed to cover the wiring layer, wherein the substratefor suspension comprises a first structural part including the metalsupporting substrate, the insulating layer, the wiring layer, and thecover layer, and a second structural part in which at least theinsulating layer is continuously formed from the first structural part,in a planer view from a laminate direction of the metal supportingsubstrate, the insulating layer, the wiring layer and the cover layer,and the second structural part has no metal supporting substrate, andwherein the first structural part and the second structural part areadjacent in a longitudinal direction of the wiring layer in a planerview from the laminate direction, and at least one of a width from anedge of the wiring layer to an edge of the insulating layer and a widthfrom the edge of the wiring layer to an edge of the cover layer islarger in an area including a boundary between the first structural partand the second structural part than other areas in a planar view fromthe laminate direction.
 2. The substrate for suspension according toclaim 1, wherein a position of the edge of the insulating layercoincides with a position of the edge of the cover layer in the areaincluding the boundary between the first structural part and the secondstructural part.
 3. The substrate for suspension according to claim 1,wherein a curved structural section is formed so as to include theboundary between the first structural part and the second structuralpart in planar view from the laminate direction, on at least one of theinsulating layer and the cover layer.
 4. A substrate for suspensioncomprising a metal supporting substrate, an insulating layer formed onthe metal supporting substrate, a wiring layer formed on the insulatinglayer, and a cover layer formed to cover the wiring layer, wherein thesubstrate for suspension comprises a first structural part including themetal supporting substrate, the insulating layer, the wiring layer, andthe cover layer, and a second structural part in which at least theinsulating layer is continuously formed from the first structural partin a planer view from a laminate direction of the metal supportingsubstrate, the insulating layer, the wiring layer and the cover layer,and the second structural part has no metal supporting substrate, andwherein the first structural part and the second structural part areadjacent in a longitudinal direction of the wiring layer in a planerview from the laminate direction, and an auxiliary wiring layer notconnected to an outside is formed between an edge of the wiring layerand an edge of the insulating layer so as to cross the boundary betweenthe first structural part and the second structural part in planar viewfrom the laminate direction.
 5. The substrate for suspension accordingto claim 4, wherein a surface of the auxiliary wiring layer is coveredwith the cover layer.
 6. The substrate for suspension according to claim4, wherein a wiring plating section is formed on a surface of theauxiliary wiring layer.
 7. The substrate for suspension according toclaim 4, wherein at least one of a width from the edge of the wiringlayer to the edge of the insulating layer and a width from the edge ofthe wiring layer to an edge of the cover layer is larger in an areaincluding a boundary between the first structural part and the secondstructural part than other areas in planer view from the laminated layerdirection.
 8. The substrate for suspension according to claim 1, whereinthe metal supporting substrate has a tongue section for mounting adevice and an outrigger section positioned outside the tongue section;and the wiring layer is formed between the tongue section and theoutrigger section in planar view.
 9. The substrate for suspensionaccording to claim 4, wherein the metal supporting substrate has atongue section for mounting a device and an outrigger section positionedoutside the tongue section; and the wiring layer is formed between thetongue section and the outrigger section in planar view.
 10. Thesubstrate for suspension according to claim 8, wherein the metalsupporting substrate has a crossbar connecting the tongue section withthe outrigger section; and the metal supporting substrate of the firststructural part is the crossbar.
 11. The substrate for suspensionaccording to claim 9, wherein the metal supporting substrate has acrossbar connecting the tongue section with the outrigger section; andthe metal supporting substrate of the first structural part is thecrossbar.
 12. The substrate for suspension according to claim 8, whereinthe metal supporting substrate has a trace support tab on an end surfaceof the tongue section side of the outrigger section; and the metalsupporting substrate of the first structural part is the trace supporttab.
 13. The substrate for suspension according to claim 9, wherein themetal supporting substrate has a trace support tab on an end surface ofthe tongue section side of the outrigger section; and the metalsupporting substrate of the first structural part is the trace supporttab.
 14. The substrate for suspension according to claim 8, wherein themetal supporting substrate has a base part supporting a bottom of theoutrigger section; and the metal supporting substrate of the firststructural part is the base part.
 15. The substrate for suspensionaccording to claim 9, wherein the metal supporting substrate has a basepart supporting a bottom of the outrigger section; and the metalsupporting substrate of the first structural part is the base part. 16.The substrate for suspension according to claim 8, wherein the metalsupporting substrate of the first structural part is the tongue section.17. The substrate for suspension according to claim 9, wherein the metalsupporting substrate of the first structural part is the tongue section.